A wide variety of cosmetic compositions containing self-tanning agents have been used to increase the pigmentation of the skin. These compositions have been used to create artificial tans, bronzing the skin in a similar fashion to exposure to the sun. These compositions are typically quite unstable, having poor shelf life. This is thought to be due to the highly reactive nature of the self-tanning agents therein.
The prior art teaches several solutions to the problem of stability of self-tanning agents in cosmetic compositions. U.S. Pat. No. 6,231,837 B1 teaches the use of polyethoxyglycols such as ethoxydiglycol and polyols to stabilise self-tanning agent-containing compositions. WO 98/00098 teaches the combination of self-tanning agents and cross-linked non-emulsifying siloxane elastomers to form stable emulsions. U.S. Pat. No. 6,197,287 discloses anionic polymers and compositions comprising them, including self-tanning agents. However, these solutions are not entirely satisfactory at maintaining the stability of self-tanning agent-containing formulations or have other disadvantages such as poor skin feel when topically applied.
It is desirable to provide stable cosmetic compositions comprising a self-tanning agent to provide a unique level of skin tanning that lifts the skin tone. Furthermore, it is desirable to provide a cosmetic composition comprising both self-tanning skin colouring agents and chronic skin care actives that act synergistically to maximise skin tone enhancement. It is further desirable to include chronic skin regulating agents in the compositions of the present invention to improve the skin barrier and so minimise any areas of dry or compromised skin. This is desirable as dry skin areas have uneven uptake of colour resulting in a blotchy or patchy result.
A supplier brochure by SEPPIC (XP-002260687), entitled “Simulgel™ NS—An emulsifying/thickening polymer . . . for New Sensations” disclose a self-tan gel-cream composition comprising 5% by weight Simulgel NS and 2.00% by weight dehydroxyacetone, but no humectant.
A summary of a poster by T. Kurz (P043, “The Color of DHA Tan”) presented at an International Federation of Societies of Cosmetic Chemists (IFSCC) conference in Venezia (1994) relates to the possibilities to influence the hue of a DHA tan. The influence of having a moisturizer is discussed, and according to this document, “addition of 10% moisturizer does not increase the intensity of the tanning, it even seems to lead to a slight reduction of it”. Different results were obtained at a level of 20% moisturizer.